For example, in the recent research by La Motta et al. (2017), in their research in
the treatment of municipal water using electro-disinfection method by the generation
of free chlorine which concertation of 1500 mg/l and IrO 2 electrodes shows that this
indirect electro-oxidation process can remove E. Coli to about 99%. Moreover, they
claimed that using free chlorine might lead to the formation of another hazardous
material such as organic- chlorinated species which can persist in degrading and
staying a long time in the environment. To overcome the above problem, a new
research methodology developed by Ahmadi and Wu (2017) showing that using
other oxidants such as C 2 O 62
À , S 2 O 82
À , and P 2 O 84 which are electrochemically
formed using PbO 2 and boron-doped diamond electrodes can altogether remove the
organic pollutant with no formation of organochlorinated species. However, its
application in water disinfection is limited due to the type of oxidants added to
disinfect the bacteria, for example, according to Qi et al. (2018), adding activated
persulfate to generate oxidant can remove E. coli O157: H7 and Listeria
monocytogenes completely in 120 s. However, in another study by Xing et al.
(2018), using phosphate for the generation of oxidants can remove Mycobacterium
avium, Aeromonas spp., Pseudomonas aeruginosa, Hartmannella vermiformis, and
Mycobacterium spp. and resistance to Klebsiella pneumoniae, so more research must
be carried out in the future to solve its limitation to apply on a large scale.
In general, from all electrochemical disinfection approaches, direct electrooxidation using boron-doped electrodes showed high efficiency in electrochemical
water treatments due to its excellent properties such as very low capacitance,
extreme electrochemical stability, and high charge diffusion pathway, enhanced
separation of photogenerated charges, and high oxygen potential for generation of
oxidants. Therefore, it would be useful to find the proper posttreatment and method
of recovery of the electrochemical material electrode. This will be a critical factor in
the future to apply these materials on a large scale under visible light for water/
wastewater disinfection.
7.7 Future Perspectives
Nanostructured materials as photocatalyst have a great significance in the field of
water disinfection of bacterial cell and wastewater treatment of organic pollutants.
However, the study on the specific morphology and reactor design of nanostructure
material as a photocatalyst is extremely promising for the disinfection of bacterial
cells with the utilization of green technology and genetic technology but its application at large scale is still on the initial stage. Therefore, the following research
areas should be carried out in the future:
1. Most of the previous studies on water disinfection using photocatalyst are under
visible light and ultraviolet irradiation. However, recent studies show that integrating visible light and ultraviolet irradiation as photocatalyst material is highly
efficient for the disinfection process because it accounts 44% sunlight spectrum
7 Photocatalytic Nanomaterials for Bacterial Disinfection
233
the treatment of municipal water using electro-disinfection method by the generation
of free chlorine which concertation of 1500 mg/l and IrO 2 electrodes shows that this
indirect electro-oxidation process can remove E. Coli to about 99%. Moreover, they
claimed that using free chlorine might lead to the formation of another hazardous
material such as organic- chlorinated species which can persist in degrading and
staying a long time in the environment. To overcome the above problem, a new
research methodology developed by Ahmadi and Wu (2017) showing that using
other oxidants such as C 2 O 62
À , S 2 O 82
À , and P 2 O 84 which are electrochemically
formed using PbO 2 and boron-doped diamond electrodes can altogether remove the
organic pollutant with no formation of organochlorinated species. However, its
application in water disinfection is limited due to the type of oxidants added to
disinfect the bacteria, for example, according to Qi et al. (2018), adding activated
persulfate to generate oxidant can remove E. coli O157: H7 and Listeria
monocytogenes completely in 120 s. However, in another study by Xing et al.
(2018), using phosphate for the generation of oxidants can remove Mycobacterium
avium, Aeromonas spp., Pseudomonas aeruginosa, Hartmannella vermiformis, and
Mycobacterium spp. and resistance to Klebsiella pneumoniae, so more research must
be carried out in the future to solve its limitation to apply on a large scale.
In general, from all electrochemical disinfection approaches, direct electrooxidation using boron-doped electrodes showed high efficiency in electrochemical
water treatments due to its excellent properties such as very low capacitance,
extreme electrochemical stability, and high charge diffusion pathway, enhanced
separation of photogenerated charges, and high oxygen potential for generation of
oxidants. Therefore, it would be useful to find the proper posttreatment and method
of recovery of the electrochemical material electrode. This will be a critical factor in
the future to apply these materials on a large scale under visible light for water/
wastewater disinfection.
7.7 Future Perspectives
Nanostructured materials as photocatalyst have a great significance in the field of
water disinfection of bacterial cell and wastewater treatment of organic pollutants.
However, the study on the specific morphology and reactor design of nanostructure
material as a photocatalyst is extremely promising for the disinfection of bacterial
cells with the utilization of green technology and genetic technology but its application at large scale is still on the initial stage. Therefore, the following research
areas should be carried out in the future:
1. Most of the previous studies on water disinfection using photocatalyst are under
visible light and ultraviolet irradiation. However, recent studies show that integrating visible light and ultraviolet irradiation as photocatalyst material is highly
efficient for the disinfection process because it accounts 44% sunlight spectrum
7 Photocatalytic Nanomaterials for Bacterial Disinfection
233